In a refrigerator using a flammable refrigerant such as isobutane, when the flammable refrigerant leaks from the refrigeration cycle, there is the potential for the leaking flammable refrigerant to ignite if the leaked concentration is within a flammable range and there is an ignition source nearby.
For this reason, an invention that detects flammable refrigerant leaks has been proposed. The invention reduces the danger of ignition of the flammable coolant by monitoring load variations in the refrigeration cycle when the drive circuit of a brushless DC motor driving the compressor is driven by an inverter motor drive by PWM control, so that when there is a specific load variation, it determines that there is a refrigerant leak and stops the power distribution with respect to parts such as electrical parts (e.g., Japanese Patent Application No. 2002-010817).
Namely, when a flammable refrigerant leaks from the refrigeration cycle of the refrigerator, the load of the compressor supplying the flammable refrigerant to a refrigerant flow path varies greatly. Thus, this load variation is determined by measuring the duty value of the PWM-controlled compressor, and it is determined that there is a flammable refrigerant leak when the rate-of-change of the duty value varies within a predetermined range.
However, with this invention, when a variation occurs in the direct-current power voltage supplying direct-current power to the compressor, the duty value changes without relation to the load variations in the refrigeration cycle, so that there is the potential to erroneously detect, from the change in the duty value, that there is a flammable refrigerant leak despite the fact that, in actuality, there is no flammable refrigerant leak.
Thus, in light of this problem, the present invention provides a refrigerant leak detector of a compressor that can prevent the erroneous detection of a flammable refrigerant leak even if the direct-current power voltage varies.